Slate is presented as a covering material, widely used in some regions of the world, which provides construction with an important amount of naturalness and beauty. Its exceptional behavior as regards the impermeability achieved on covers and its durability is remarkable (slate offers a 50 year durability warranty, which is impossible to achieve to this day by covering materials of synthetic origin).
As major weaknesses of slate we can mention its relatively high cost, due to the fact that the material itself results from a highly wasteful and mainly manual manufacturing process, and especially because the installation is slow and it implies the use of a large number of slate per square meter. On the other hand, the highly skilled labor required also has an influence on the product cost and on the limitation for entering new markets.
Slate is traditionally fixed mainly by two different systems:
A first method by nail fixing, characterized by:                A part by part installation, with two nails per part. This causes the slowness of the installation, as well as possible slate breaking problems.        Need for an initial on site layout, both vertical and horizontal, for the subsequent placing of slate parts, which has a negative impact on productivity.        
A second method by hook fixing which is also characterized by:                Its part by part installation, which makes it a slow process.        Need for an initial on site layout, both horizontal and vertical, which has a negative impact on productivity.        Fastening elements for the visible slate parts.        
In general, solutions collected in prior art for fixing slate on covers are complex solutions requiring equally complex elements that do not allow simple access thereto. This generates cumbersome assemblies, difficult to carry and handle, increasing the price of the whole manufacturing process without the advantages thereof overcoming the problems.
Nowadays, the market goes in two directions, on the one hand technology is evolving along lines seeking the reduction of installation complexity. This is the case of the installation system known as project PGIDIT06DPI201E, as well as other existing products in the market with lesser scope and more limited capabilities.
On the other hand, “artificial” elements that are intended to imitate the natural appearance of slate are used. This is the case of ceramic tiles, the range of which includes dark grey flat parts that are presented with a finish similar to that of slate, although always without the natural appearance thereof. They are regular elements with an artificial appearance.
In this regard, we can highlight layer-type bituminous materials, designated as Shingle, whose shape corresponds to flat rectangular parts having a rough surface, the life of which is always limited to a maximum of around 20-25 years.
It should also be emphasized the use of metal or plastic plates imitating the slate finish, which do not satisfactorily achieve said finish nor have the same capabilities offered by natural slate, as regards durability, resistance to UV radiation, resistance to bending, impermeability, . . . derived from their physical and superficial properties.
Thus, although these products have a reduced cost and are quickly installed, neither their appearance nor their durability is by any means comparable to those of a natural slate cover (especially those made of plastic materials).